Propelling system and method



March 13, 1928. i 1,662,206

C. M. PAXTON PROPELLING SYSTEM AND METHOD Original Filed April '7. 1923 4 Sheets-Sheet 1 avwemto'c 3513M item; I

March 13, 1928. 6 1,662,206

I c. M. PAXTON PROPELLING SYSTEM AND METHOD Original Filed April 7. 1923 4 Sheets-Sheet 2 7 March 13, 1928.

' 1,662,206 c. M. PAXTQN PROPELLING SYSTEM AND METHOD Original Filed April 7, 1923 4 Sheets-Sheet 5 Svwemtoz awrmlimw 32x 4% 6mm;

March'13, 1928. 1,662,206

C. M. PAXTON PROPELLING SYSTEM AND METHOD Original Filed April v; 1923 4 Sheets-Sheet 4 avwentoz Patented Mar. 13,

UNITED STATES PAJTENT OFFICE.

CLIFFORD I. PAXTON, OF BROOKLYN, NEW YORK, ASSIGNOB TO PAXTON CORPORA- TION OI AMERICA.

LIPZBQOIIIJIiI'JIPnl'G- SYSTEM AND METHOD.

My present invention concerns certain modifications, features and details of construction shown and described but not claimed in my prior application, Ser. No. 630,463, filed April 7, 1923, of which this case is a division.

In said prior application, I have shown, described and claimed broadly a novel system and method which may be briefly referred to as involving the use of-relatively high velocity, small volume, jets, discharged rearwardly and outwardly from submerged nozzles on the bow of a ship located in ad- Vance of and discharging through-the region below where the maximum bow wave would normally tend to pile up, an important feature being lengthwise fitting of the jet stream to the appropriate sections of the ships length. An essential featureis shortening and concentrating the useful water excavating portion of the jet streams by suit-.

ably proportioning their surface areas to cross-sectional velocity. The more the surface area is increased, as by flattening and elongating the nozzle orifice, the shorter, quicker and more concentrated will be the excavating action. 'When the jet streams are thus fitted for maximum excavating etiect throughout the high pressure regions of the entrance section, the transition portion of the stream where it rapidly decelerates and loses its excavatin capacity, naturally becomes located along te midship section of thevessel and in the preferred models of the hull still more sluggish, water-depositing, pressure increasing portion of the jet, which I call 7 the plume, will naturally take efiect on and alongthe run section, tending to fill up the hollow left vacant by the advancing hole and tending to produce a rearwardly trending wake.

The specific modifications and details herein claimed will be more evident from the following detailed description in connection with the diagrammatical illustration in the accompanying drawings, in which Fig. 1 is a top plan of a portion of a ships hull outline partlly broken away to section on the line 1-1, ig. 2;

Fig. 2 is an end elevation -partly broken away to section on the line 2-2, Fig. 1;

serial No. 630,463. Divided and this application filed May 25, 1925. Serial No. 32,531.

similar to Fig. 1, but showing a modification, p

F1gure 7 1s a similar diagrammatic plan view show ng another modlfication;

Fig. 8 is a side elevation of the entrance section of a ships hull showing another mod-' ification; I

Figs. 9, 10 and Here respectively plan, side elevation and stern elevation of another modification.

These drawings are necessarily quite diagrammatic, particula'rl lustration of water phenomena. B is the bow; S is the stern. The submerged body from B to M is the entrance section, and from M to S is the run section.

The resistances offered by the water to the advance of a hull forced through it, as by a screw 12 (Fig. 4 upper half) include frictional resistance called skin friction, and the inertia resistances called water or residuary resistance. The latter includes the rearward pressure on the entrance section B-M, which is set up when the forward surwater outward from said surfaces as indicated b the arrows near R, Fig. 4c. The water disp need is confined by the outlyingmass water so that the ressure increases from the bow rearwardly utnon-uniformly becoming an accentuated maximum somewhere about R resulting in the well-known ,bow

in the attempted ilfaces start and accelerate flow of the inert wave, which breaks away from the hull as Aft of the midship section there are hollows and subnormal pressures about the run M-S due to hull suction or more properly speaking, cavitation, into which water flows from regions H and J. The usual screw propeller would tend to excavate water from about the run, as indicated by arrows J, so that cavitation would be increased by excavation.

The above described inertia effects tend to create a rearward pressure differential.

While skin-friction increases in a ratio less than the square of the speed of the ship, the inertia resistances increase much more rapidly than skin-friction. For instance, in the case of a iven ship, the skin-friction may amount to l0% or more of the total resistance at so-called low speed, while at higher speed the water resistance may become or more of the total, notwithstanding the simultaneous increase in skin-frictional resistance. 7

While my invention involves modifying the effects of skin-friction as concerns resistance to the ships movement, it is primarily directed against said inertia resistances.

Referring to Figs. 1, 2 and 3, and the lower half of F 4, it will be seen that the jet nozzle 1 is eeply submerged and discharges rearwardly.. The initial jet stream water as widened by deceleration only is indicated by the lines a, a. The stream is confined by sharply defined walls of mass water so that all friction, cohesion and impact op erate to pick up the water and carry it off as indicated by the lines a, 0, c and b, b, b. This ideal utilization of friction to remove water is an important feature of my invention. The removed water is replaced by inlow at right angles to the jet stream surface as indicated by the short arrows at c, c and b, b, but a stream of easily attainable, high velocity will excavate and carryofi the water so rapidly that it produces a powerful suction effect as regards adjacent water and hull surfaces which are not beyond effective range thereof. These subnormal pressures tend to take effect as surface depressions and where these are caused to develop about the entrance section of a moving boat as shown in Figs. 5 and 8, there may be distinct hollows or depressions W at or near the place where the b0w wavewould otherwise be. The near surface water encountered by that part of-the hull which is being pushed ahead of the nozzles, tends to flow parallel with. the hull surface into said depressions somewhat as indicated at B, Fig. 4.

The jet stream is slowed down by the water it picks up until it ceases to be effectively useful for water-excavating and be and this point, indicated as at M in the rawlngs, the stream, being opposed by the relatively stationary mas water,-naturally tends to set up sub-surface pressure, causing the stream to pile up or plume, as I call it.

This part of the jet stream is caused to develop in the area P so that it flows about the aft or run section of a moving ship into the subnormal pressure regions, where it may result in a wave of a sort heretofore unknown in the art. This may be called the run-wave, and it may be somewhat as indicated at W", Figs. 5, 8 and 11. In many cases this part of the stream will be so located and of such volume and velocity as to more than fill up the space the ship moves out of, thus resultin in a rearward trending wake, as at D. The above factors are variable, and even in a well designed system the trend may be somewhat forward instead of aft.

The flow-inducing portion of the stream may be shortened and its effects concentrated and confined to the dimensions of the desired region of the hull in any given case orifice is shown as a long narrow slot 6 extending nearly parallel with the hull surface 2, and in the present case extending along one-third or more of the surface approximately midway between the keel at A and the surface of the water W. This will give a stream which, when built up at top and bottom by induced flow can reach the surface and the keel as indicated in Fig. 5, and in combination with another similar jet on the other side of the ship, may entirely surround the midship section with a stream of rearwardly flowing water. The width of this slot has been carefully proportioned to its length so that the jet stream will have its surface of contact with the outside water of such large area that its energy will be utilized and exhausted to the desired extent, in the high ressnre region, before it passes the end of t e entrance section at M. The

lUO

principle is that a jet stream of given crosssection and velocity has the least possible surface area per unit length and its waterexcavating portion will be of maximum length when the nozzle orifice is circular so as to'make the stream cylindrical but if the nozzle orifice be made long and narrow without substantially changin its outlet area so that the jet stream wi l he a thin sheet having, per foot of length, ten times as much flow nducing surface area as the corresponding cylindrical stream, its flow inducing action will be concentrated so that the same total volume of water will be removed from a region one-tenth as long, in one-tenth the time. This is of greatest impprtance because effectiveness in removing inertia pressures depends entirely upon rapid removal as compared with the rate at which outside water can flow in response to the suction or subnormal pressures created by such removal.

I have found that immediately outside the skin of a jet stream there is. an area, or thin stratum, of negative pressure, the value of which may be read upon a gauge attached to an impact tube. I have discovered by test that such negative pressure exists and results in a suction effect which I I utilize 7 as an effective propelling factor.

This suction effect is normally equal on opposite faces of the jet stream, but by making the bow jet streams in the form of sheets discharged at a proper outward angle which, in the case of Fig. 3, is about M'degrees, the suction and pressure-reducing effect developedby the inner surface of the jet stream, as indicated by the arrows b, b, will take effect on the hull. This has the double advantage of using the water-excavating capacity of the inner face of the jet Stream This is not necessarily essential but now seems preferred for mechanical reasons, and because it offsets the initial portion of the jet stream from the hullsurface, thus facilitating suitably restricted inflow of outside water between the stream and the hull surface with less outward angle of projection for the streams.

. To the extent that the hull ofa ship is surrounded by the rearwardly flowing streams induced by my method, the surface is shielded from impact of and normal frict1on with the mass water through which the hull is being propelled, and inertia and skin-frictional resistances are thereby respectively reduced and modified.

In Figs. 1, 2 and 3, 2 is the shell-plating of the ship, 1 is the nozzle, and 3 is the connection for a supply of water under pressure. 4 is a plate, preferably though not necessarily, integral with the nozzle. 5 is a detachable mouth-piece in which is a suitable orifice 6. While thisis shown as a slot, much the same effect will be produced from the use of a row or series of circularorifices, the streams from which would blend to form a sheet a short distance from the nozzle. The shell-plating 2 may be cut. away as at 7, to permit attaching the nozzles and per-.

mitting them to pass through the ships side.

downward angle for the nozzle.

Similar construction has been employed for a wooden hull. Rivets, bolts, welds or other fastenings are assumed.

By having the nozzle tips readily detachable from the exterior of the ship, the orifice dimensions or angle of discharge may be easily altered; also renewals of mouth-pieces may be easily made as necessary. Screws or bolts for this purpose are indicated in. Fig. 2.

In Fig. 4 the water is supplied to nozzle 1 at 3.-by means of pipe 8 of a'system connected to a centrifugal, rotary or other suitable type of pump 9, driven by a turbine,v

rotary engine or other suitable prime mover- 10. The prime mover is shown as directlyconnected to the pump through shaft 10,

but it will be obvious that gears may be interposed. In Fig. 5 is shown a desirable arrangement of the intake 11, aft of the nozzles and near the keel so that they will not beexposed in rough water.

The nozzles are located well forward,

preferably somewhere between one-fifth and one-third of the distance from the cutwater to the end of the entrance section, the main consideration bemg that they should be placed forward of the region of maxlmum adverse rearward pressures where the bow-wave piles up just before leaving the ships surface.

. Fig. 5 shows the hollows created by the jets on either side of the entrance and the -wave running on either side of the run.

Lines a and a have the same slgmficance' as in Fig. 1 while e, e and e and d, d and d plume area that is, the water deposi-ting' I effect of the. jets. These might be cancelled; if the shipwerepropelled at higher speeds if such speeds were gained by increasing propelling thrust without corresponding increase in water-moving power of the jets. The nozzle is directed so that normallywtheupper edge a, of the initial-or high velocity part of thestream, is directed well below the normal surface level of the water. In

the present case this requires a somewhat F-F is the so-called forefoot which is merely surface water. thrown upby the immediate prow entrance, and is not to be confused with a fully developed-bow wave."

13 is the rudder, and steering can begreatly facilitated by hydraulic means not shownor claimed as a part of my invention. The in? take 11, pump 9, service piping 8 and connection 3 to nozzle 1, respectively, may be the same as in Fig. 4:.

Fig. 6 shows how a plurality of overlapping jets may be employed as when a widely variable speed range might be desirable. Variable speed through a considerable range is possible without the use of overlapping jets but a jet is more efficient at the speed for which it is designed and it may be desirable to have two or more nozzles as 1, 1", discharging separate streams, each properly fitted to the length of the hull, and either one or each of them designed to propel the ship at normal full speed when operating alone; then when both jets are turned on they can be made to deliver a correspondingly greater stream of water at less ve' locity, thereby increasing the proportion of the power applied as thrust. This is particularly useful for low speeds where inertia resistances are a small factor. More than two jets may he used, either separately or' together, and fitting the hull either at the same speed or different speeds and when discharged either at the same velocity or different velocities. The space N is optional.

Fig. 6 also shows the combination of my system with a screw propeller 12'. Dotted line Q indicates the above-water outline of the hull of the ship at the stern. For such use in combination with a propeller, it seems preferable to employ high velocity jets of relatively small volume, more or less highly developed as to surface, to excavate water from about the entrance and more it aft, thus reducing the resistance to be overcome by the screw. Hence, if my system is to be applied to a ship already equipped, a screw propeller of greater pitch might be required.

Fig. 7 illustrates the a plication. of my system of propulsion to a s lip having a considerable length of parallel body. 1 and 1 are the nozzles for excavating water from about the entrance and filling in about the run, respectively. M and M" indicate the parallel body. B and S are the how and stern, respectively. The areas within the curved lines P and P are the respective plume areas. Ships with exceptionally bluff bows are apt to have a long parallel body so that short, highly developed and high velocity jets may be used at the bow, while parallel body jets operating at lower velocity perhaps and at an angle far more efficient than the bow-jets may be employed to afford the main propulsive effort.

Fig. 8 shows how horizontal subdivision of the jet sheet is possible in cases where a single sheet might have practical disadvantages; as where it is too broad to permit a sufficient volume of mass water to flow inbehind it from top and bottom. This arrangement simply divides the sheet into two or any number of sheets, and allows space illustrated by K, between the sheets for the inflow of mass water. 1 and 1" are the nozzles. B, M, W, V, W" and L have the same significance as in Fig. 5; as do also the short arrows and the lines leading from them. FF is the forefoot, which is not to be confused with a fully developed bowwave as stated in connection with Fig. 5. The functioning will be clear from explanations previously given. \Vith this arrangement (as also that shown in Fig. 6), the sheets combine to form a single stream at no great distance from the nozzle orifice. One of the streams may be shut off without seriously modifying the action of the other. For instance, the top stream might be shut off to save ower when the ship is running light and oats high in the water, or for other reasons.

\Vhile my system is applicable for almost any vessel of the displacement type having well-defined entrance and run sections, some ship forms are better adapted than others to utilize the advantages of my system.

A bull illustrating certain features of adaptation is shown in Figs. 9, 10 and 11. Fig. 9 is a plan outline of the hull just above the turn of the bilge about on the line 9-9, Figs. 10 and 11. The entrance section from B to M is approximately one-third the length of the boat. Actually the maximum cross-section is slightly aft of M but between M and M the curvature is so slight that its effect does not differ much from that of a parallel body section. Hence we have from M to S a section approximately twice as long as the effective entrance section, giving much greater opportunity for the sheath stream to decelerate and plume effectively within the long area P. This permits of much higher midship velocity for the cumulative jet stream at M, without sacrificing effective development of plume pressures and filling in of hollows about the run section.

Fig. 11 is a rear view showing the midship outline M, the stern outline S, and a characteristic intermediate section SM,indicating through what a long distance and at what effective angles the plume may develop and apply helpful pressures about the run.

Other minor but useful features are the header 8 extending through the bow of the ship which supplies the jets 1 1 and which is supplied by the pumps, not shown, through conduit 8. Another point is the location of the intake 11 which is in the bottom of the ship not far forward of the midship section, where it will always be submerged in solid water even in the roughest weather. This is important because while nozzle reaction of the jets and the consequent load on the pump and engine are approximately constant, regardless of whether the jets come out of the water or not, exposure of the intake and suction of air therethrough would cause the propelling thrust to fail and the engine to race, both of which would be very objectionable from the viewpoint of practical utility.

In these figures the Water line WV, W, forefoot F-F, hollow -VV, run-wave WV", and et stream lines have the same significance as in the preceding figures.

So far as concerns the basic principles of my method, it will be evident that these may be utilized even more consistently under a wide range of conditions if the nozzles are adjustable while running, as to area, or contour, or angle, or all three.

-While some of the fundamental principles of my invention are ca able of application to air jet propulsion of odies submerged inv air, it will be evident that the application of said principles will require material modification because of the materially different functioning. of both the jet stream and the resistance medium by reason of the fact that air is easily expansible and compressible, has little weight, inertia ormomentum, and no cohesion, surface tension or viscosity; all contrasting with water which is preferably inexpansible and incompressible; has great weight, inertia and momentum; and has marked cohesion, surface tension and viscosity.

While I have described and illustrated with considerable particularity various 0L the vessel at rates requiring the resistance removing and propulsive factors that may be involved in the practice of my present invention, it will be understood that the experimental data and calculations are for illustrative purposes and that my broad principle of fitting the different characteristic portions of the jet to the appropriate characteristic sections of the ship can be applied in practice without reference to any such data and without reference to the theories which I have advanced as reasonably accounting for the remarkable results achieved.

I claim:

' 1. A marine. vessel of the displacement type, having entrance, midship and run sections, in combination with a propelling sys- .tem including a power driven propelling wheel and resistance reducing means including a power-driven, high pressure pumping means fordischarging high velocity jets of water, designed and arranged to exert their useful water excavating action along the entrance section and beneath where the maximum bow waves tend to pile up when the vessel is driven at speed by the combined efforts of the wheel and the jets.

2. A marine vessel of the displacement type, in combination with propulsion means,

including motor driven pumping apparatus operatively connected with submerged fixed nozzles designed to discharge rearwardly jets of water of shape, surface area and outward angle from an adjacent submerged surface of the vessel designed to cause the jets to fit about the hull for removal of water resistances, said nozzles being formed with nozzle tips removable and replaceable from the exterior of the vessel. H 4 3. A marine vessel of the displacement type, in combination with propulsion means,

including motor driven pumping aparatus' operatively connected with submerged nozzles deisgned to dischar e water rearwardly at a substantial outwar angle from an adjacent submerged surface of the vessel through exteriorly projecting conduits converging toward slot-like outlets ofcross-sectional area substantially greater than the operatively connected'withsubmerged noz- .zles on. either sideof the bow located in ad vance of and discharging high velocity water jets through regions where the maxi: mum bow wave tends to pile up, together with supplemental" screw propulsion means adapted to apply forward tl rust propellin displacement 0 water in amounts exceedm'g' ithe water excavating capacit of the jets.

5.'The metho of propelling marine vessels of the displacement type, which consists in generating power within the ship and ap-' plying part 0 it to a screw exerting effort at the stern and part of it through rearwardly directed jets of water arranged to excavate water from the entrance section to decrease the water resistance opposing the screw propelling efiort.

' 6. The method of propelling marine vessels of the displacementtype,'which consist in generating power within the ship and ap} plying part of it to a screwexertm' effort at the stern and part .of it throug' rearwardly directed jets of water arranged to have their useful water excavating portions localized along the entrance section, as and for the purpose described.

7. The method-of propelling marine vvessels of the displacement type whichconsists in generating ower within the ship and applying part 0 it to a screw exertm at the stern and part of it throug high velocity rearwardl directed jets of water arranged to deposit water of low velocity.

adjacent the run section to decrease the cavitation caused by the screw.

8. The method f propelling' marine vessels of the displacement type, which consists lie in generating power Within the ship and applying part of it to a screw exerting effort at the stern and part of it through rearwardly directed jets of water arranged to deposit water adjacent the run section to decrease the cavitation caused by the screw and to excavate water from the entrance section to decrease the water resistance opposing the screw propelling effort.

9. In combination with a vessel having a main propelling means, speed increasing means for the vessel including a pump mounted on the vessel, an intake pipe for the pump arranged to receive water from adjacent the entrance section of the vessel, and outlet pipes extending below the water line rearwardly of the bow of the vessel and arranged to expel the water from the pump in divergent streams directed rearwardly of the vessel, said outlet pipes being provided with a plurality of spaced apertures for directing jets of water from adjacent the lowermost portion of the vessel to the water line.

10. In combination with a vessel having a main propelling means, speed increasing means for the vessel including a pump mounted on the vessel, an intake pipe for the pump arranged to receive water from adjacent the entrance section of the vessel, and outlet pipes having a plurality of spouts on each side of the vessel extending below the water line rearwardly of the bow of the vessel and arranged to expel the water from the pump in divergent streams directed rearwardly of the vessel.

11. In combination with a vessel having a main propelling means, speed increasing means for the vessel including a pump mounted on the vessel, an intake pipe for the pump arranged to receive water from adjacent the entrance section of the vessel, and outlet pipes having a plurality of spouts on each side of the vessel extending below the water line rearwardly of the bow of the vessel and arranged to expel the water from the pump in divergent streams directed rearwardly of the vessel, said spouts having a plurality of spaced apertures extending from adjacent the lowermost portion of the boat to the water line.

12. In combination with a vessel having a main propelling means, speed increasing means for the vessel including a. plurality of nozzles arranged below the water line at each side of the boat rcarwardly of the bow, and .means for forcibly expelling water from said nozzles indivergent streams directed rearwardly of the vessel, said nozzles being provided with a plurality of spaced apertures extending from adjacent the lowermost portion of the vessel to adjacent the water line.

13. In combination with a vessel having a main propelling means, speed increasing means for the vessel including a pair of spaced nozzles arranged below the water line at each side of the boat rearwardly of the bow, and means for forcibly expelling water from said nozzles in divergent streams directed rearwardly of the vessel, one nozzle of each pair being located closer to the widest portion of the boat.

Signed at New York city, in the county of New York and State of New York, this 22d day of May, A. 1)., 1925.

CLIFFORD M. PAXTON. 

